规则波中船舶非线性波浪弯矩的时域计算

CALCULATION OF SHIP NONLINEAR BENDING MOMENT IN REGULAR WAVES IN TIME DOMAIN

本文提出了一种预报船舶在迎浪规则波中升沉和耦合运动以及垂向弯矩的非线性响应的方法。本方法的实质是线性切片理论的延伸与推广,它在原切片理论的载荷公式中加入了非线性的浮力项、非线性的流体动量力及阻尼力项。在时域中求解耦合运动方程组,在此基础上分别求解将船体视为刚体和弹性梁的垂向弯矩。此非线性理论计算值与线性理论计算值及模型试验结果作了比较,非线性计算模拟与模型试验结果一般可达到良好的一致性。在船舶总纵强度研究有特定价值的波长范围内,本方法能有效地用来预报垂向弯矩,

Coupled motion equations are solved in time domain, based on which the vertical bending moments of the hull are obtained for both cases when the hull is either considered as a rigid body or as an elastic body.The results are compared with those obtained from linear theory as well as model tests. Good agreement is achieved between the non-linear computer simulations and the experimental data. It is shown that the method can be used to predict the vertical bending moments in the range of those wave lengths which have significant contribution to the longitudinal strength of ships. It is sure that the current method may be further developed to determine the extreme bending moments and improve the existing regulations for calculating the strength of ships.